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Finding the Fourth Proportional to 1,005.12, 1,387.56 and 655.80

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Solution

The fourth proportional to 1,005.12, 1,387.56 and 655.80 is: 905.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,005.12 : 1,387.56 = 655.80 : x
  2. Step 2: Convert to fraction form
    1,005.12/1,387.56 = 655.80/x
  3. Step 3: Cross multiply
    1,005.12x = 1,387.56 × 655.80
  4. Step 4: Simplify right side
    1,005.12x = 909,961.85
  5. Step 5: Solve for x
    x = 909,961.85/1,005.12
  6. Step 6: Final answer
    x = 905.33

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.